Dotyophycus pacifi cum I . A . Abbott ( Liagoraceae , Rhodophyta ) a new record for the Atlantic Ocean

(Dotyophycus pacifi cum I. A. Abbott (Liagoraceae, Rhodophyta) a new record for the Atlantic Ocean). Specimens of Dotyophycus pacifi cum I. A. Abbott were found during a survey of Rhodophyta on the coast of Bahia state. Th e samples were taken from 23-36 meters depth and the specimens found were studied in detail and compared to other morphologically similar species. Th is is the fi rst time that the genus Dotyophycus is cited for the Atlantic Ocean.


Introduction
Th e majority of rhodophycean species from the Bahian coast are largely distributed in the western American tropical region and in the tropical area of the Indo-Pacifi c in a smaller fraction.According to Horta et al. (2001), the Brazilian and Caribbean seaweed fl ora have both originated in the Indo-Pacifi c region.
A detailed exploration of the subtidal zone has revealed many little-known and previously unreported taxa that are new for the Brazilian coast and the Atlantic Ocean (Nunes et al. 2008a, b;Nunes & Guimarães 2008).
Th e genus Dotyophycus was described by Abbott (1976) based on the details of origin of the carpogonial branches, the manner of initiation of gonimoblast and the subsequent fusion cells of the carpogonial branch with the lower gonimoblastic cells.According to Abbott and Yoshizaki (1981), this genus is described as having a calcifi ed thallus, brittle when dry and a cylindrical-compact axis.Th e thallus is multiaxial, branching dichotomous to subdichotomous, and the cortical or assimilatory fi laments present terminal cells of diff erent forms.Th e carpogonial branch originates from the medullar region through a modifi ed cortical fi lament, producing 3 to 4-celled carpogonial branches, with 8-10 sterile cells located below.Th ese cells can form 1-13 short lateral fi laments (subsidiary carpogonial fi laments).Gonimoblasts are formed aft er transverse division of the zygote, giving rise to radial fi laments with terminal cells that become carposporangia.Dioecious and monoecious plants, spermatangia originating in groups on peduncles.
Th ree species of Dotyophycus are recognized at present: D. abbottiae Kraft , D. pacifi cum I.A. Abbott and D. yamadae (Ohmi et Itono) I.A. Abbott et Yoshizaki, all occurring in the Indian and Pacifi c Oceans (Guiry & Guiry, 2009).Th e species D. corymbosum was described by Rishnamurthy & Sundararajan (1985) from the Indian Ocean, but aft er analyzing the type material, Abbott (1999) considered the species as being synonymous with D. yamadae.Dotyophycus was reported by Nunes (2005b) on the coast of Bahia, but due to scarce material available it was not possible to observe diagnostic features that separate the species.
Th e identifi cation of the species is based mainly on their habit, pattern of division of fertilized carpogonium, presence or absence of short lateral fi laments on the carpogonial branch and extension of cell fusions in the carpogonial branch.
Th is work describes the morphology and aspects of the reproduction of Dotyophycus pacifi cum, collected on the Brazilian northeastern coast, thus being the fi rst citation of this species from the Atlantic Ocean.

Material and methods
Th e material was collected on Bahia's coast on several beaches of Camaçari and Vera Cruz Counties, being sampled from the subtidal region (23 to 36 m) using a Holme dredge and preserved in 4% formalin/seawater.Stereomicroscope and optical microscope were used to observe the external and internal morphology.Vegetative and reproductive structures were studied through histological hand sections made with a razor blade aft er decalcifi cation with HCl 5%.Sections were stained in a solution of 1% aniline blue to which a small amount of 1 N HCl was added as a mordant.To characterize the calcifi cation pattern, specimens were air-dried, fractured and mounted on aluminum stubs.Th e stubs were then coated with gold before viewing in Zeiss Scanning Electron Microscope (SEM) at 15 kV.Th e material identified was deposited at the Herbarium Alexandre Leal Costa (ALCB) of the Department of Botany, Federal University of Bahia, Brazil.Abbott, Phycologia 15: 125. 1976. Figures: 1-22 Type-locality: Moloka'i, Hawaiian Islands.Holotype: BISH 499995.

Dotyophycus pacifi cum
Erect terete thallus, 4-6 cm in length, 0.5-1.5 mm in diameter, mildly calcifi ed at the apex heavily calcifi ed at the base, dichotomous to subdichotomously branched, occasionally geniculated at branch angles and sharpened at the tips.Th allus brittle and sometimes powdery when dried.Calcifi cation around medullary core was more conspicuous, with cortical and medullar fi laments immersed in a matrix of unbranched aragonite crystals.Th in young medullar fi laments 9-17 µm increasing in diameter in older areas to 12-25 µm.Cortical or assimilatory fi laments 260-300 mm in length, 3-5 times di-trichotomous with cylindrical cells below and large infl ated subterminal cells, each subtending 3-4 smaller obovoid terminal cells 14-20 µm in diameter and 19-38 µm in length.Rhizoidal fi laments were arising on inner cortical cells.Primary carpogonial branches originated from medulla through a modified cortical fi lament, ending with 3 to 4 celled carpogonial branch and having 8-12 sterile cells below.Short fi laments varying in number from 1-5 produced laterally from cells of the carpogonial branch.Aft er fecundation, transverse division occurs on the carpogonium base.Th e upper cell divides successively forming gonimoblastic fi laments, which are radially arranged.Terminal cells become carposporangia, carpospores individed, 7-10 µm in width and 16-30 mm in length.Cystocarp prostrate, 410-680 µm in diameter.Carpogonial branch cells and fi rst gonimoblastic cells may fuse.Spermatangial branches were not observed.
Studied Th e studied material was placed in genus Dotyophycus since it presents a long carpogonial branch of 13-16 cells that is homologous with an entire assimilatory (cortical) fi lament and a diff use, radiating carposporophyte.Also, cells from the primary carpogonial branch can originate other carpogonial branches (polycarpogonial condition).Of the more closely related genera of the family Liagoraceae (Tab.1), Liagoropsis Yamada has some affi nity with the Brazilian material.However, in Dotyophycus the carpogonial fi laments replace an entire cortical lateral, whereas those of Liagoropsis replace the primary subdivision of a cortical lateral and are also relatively compact and short (Doty and Abbott 1964;Kraft 1988).Regarding the genus Yamadaella I.A. Abbott, we also observed some similarities in relation to the position of the primary carpogonial branch and some of the post-fertilization aspects.However, the presence of uniformly three-celled, non-proliferous carpogonial fi laments and carpotetrasporangia represent important distinctive characteristics typical of the genus Yamadaella.
Among the species that belong to the genus Dotyophycus (Tab.2), the studied specimens can be identifi ed as D. pacifi cum since they present the set of features described by Abbott (1976) for this species: brittle cylindrical stem when dry; branches mainly dichotomous; absence of subsidiary cortical fi laments; rhizoidal cells present; transverse division of fertilized carpogonia followed by lateral divisions originating the fi rst cells of the diff use gonimoblast; and fusion of carpogonial branch cells and fi rst gonimoblastic cells.Th e specimens examined were collected in depths similar to those in which D. Pacifi cum from Hawaii is found indicating that this species inhabits deeper waters when compared to the other two species described in the genus.Kraft (1988) points out that only a few characteristics are available to separate the species into the genus Dotyophycus.D. pacifi cum diff ers from the other two species mainly in being monocarpogonial and in becoming geniculated upon drying.D. abbottiae and D. yamadae have compound carpogonial fi laments (Chiang & Chen 1983: Fig. 4 and 5;Kraft 1988: Fig. 7 and 14).Of the studied specimens, the majority of the assimilatory fi laments give rise to only one carpogonial branch (monocarpogonial condition, Fig. 5), even branches with four carpogonial branches can occur (polycarpogonial condition, Fig. 6 -8).Atypical cortical fi laments were also observed arising from carpogonial branches (Fig. 9).
As highlighted by Chiang & Chen (1983), the presence of compound carpogonial fi laments supports the thesis that in Dotyophycus this female structure is equivalent to an entire assimilatory fi lament, showing that each carpogonial branch represents a branch homologous to a vegetative branch of an assimilatory fi lament system.
In the Dotyophycus species, the gonimoblastic fi laments produce terminal carposporangia which very frequently present their cytoplasm, transverse or obliquely, divided in two or irregularly divided in four.Abbott (1976, Fig. 9) illustrated divided carposporangia for D. pacifi cum, although the specimens described here did not present that characteristic.
Dotyophycus yamadae (Ohmi et Itono) I.A. Abbott et Yoshizaki is the species that is most similar to D. pacificum because of the absence of cortical subsidiary filaments and the primary division of the fertilized carpogonia.However, the former has the following distinctive characteristics: compact stem, presence of cortical filaments originating from the hypogynous cell of the carpogonial filament (Chiang & Chen 1983, Fig. 2), irregularly branched cortical filaments and extensively spread gonimoblast (Table 2).
Dotyophycus abbottiae Kraft is a more distinctive species.Th e fertilized carpogonium did not divide, and two or three cylindrical gonimoblast initials are formed on its base, having a higher growth rate (Kraft 1988: 135, Fig. 12-13).In D. pacifi cum and D. yamadae, fertilization is followed by a transverse zygotic division, and this new cell laterally divides, giving rise to the gonimoblast primary cells (Fig. 9 and 10).D. abbottiae also presents subsidiary cortical fi laments and rhizoidal cells (Kraft 1988: 133, Fig. 3) and a compound carpogonial fi lament bearing up to 13 carpogonia with trichogynes.Another distinctive characteristic is the strong and continuous calcifi cation (Table 1).
Th e following set of features can be used to separate Dotyophycus pacifi cum from the other two species of the genus: calcifi cation pattern, texture, presence of subsidiary fi laments, morphology of the carpogonial fi lament and the fi rst division of the fertilized carpogonia.However, the presence of aragonite crystal among the medullar fi laments (Fig. 25) reinforces the need of SEM use to characterize   Kraft (1988) and Huisman (2006).
the diff erent Liagoraceae genera and species.Th e crystal aspect is similar to that observed by Moura et al. (1999), in Trichogloea requienii (Montagne) Kützing, and by Borowitzka (1977), in others Nemaliales genera.The seaweed flora from northeastern Brazil has similarities with the marine flora from the Caribbean region (Oliveira 2002).According to Horta et al. (2001), these similarities are due to the shared origin of the Brazilian and Caribbean fl ora in the Indo-Pacifi c region at distinct periods and routes.Some red algae considered endemic to the Indo-Pacifi c have already been referred to the southeastern Brazilian coast as Anotrichium yagii (Okamura) Baldock (Horta & Oliveira 2000), Laurencia venusta Yamada (Fujii et al. 2005) and to the northeastern Brazilian coast as Gelidiopsis repens (Kützing) Weber-Bosse (Nunes & Guimarães 2008) and Tolypiocladia sp.(Nunes 2005a), corroborating this hypothesis.
Th e uncommon presence of this genus on the coast of Bahia can be attributed to its similarity with plants of the genus Liagora, at a non-detailed view, and also to our minimal knowledge about the Brazilian subtidal seaweed fl ora (Horta and Oliveira 2001).Such examples reinforce the need to invest in the formation of taxonomists and in studies on subtidal Brazilian biodiversity.

Figures
Figures 18-22.SEM view of diff erent aspects of Dotyophycus pacifi cum I.A. Abbott: 18 -Transverse section of thallus in a cylindric portion with evident medulla (M) and cotex (C); 19 -Detail of transverse section showing medulla (arrow) and cortex with fi laments immersed in a matrix of carbonate crystals (arrow head); 20 -Detail of fi lament joining the medulla and cortex, covered by aragonite crystals; 21 -Medullar fi laments covered by aragonite crystals; 22 -Detail of cortical fi lament immersed in the carbonate matrix.

Table 1 .
Comparative features of genera of the family Liagoraceae, based on